In general, a common function for a mobile communication device is a call-receiving function. The call-receiving function indicates call-receiving most frequently via a melody mode for producing sound and a vibration mode for shaking (vibrating) the device to alert the user silently about the incoming call or other event. The vibration typically is provided by a small-sized vibration motor to transfer a vibrating force to a housing of the device, by which the device vibrates. While such vibrations are typically found in the device itself, such can be provided in an accessory case housing the device. Examples of the most common vibration motors include cylinder and pancake type motors.
For example, U.S. Pat. No. 7,446,445 of Huang discloses vibration motors and electronic devices utilizing the same. The '445 Patent describes that the vibration motor is disposed in a housing to abut the housing. A first case is disposed in the housing. A second case is combined with the first case. A magnet and a rotor are disposed between the first and second cases. A shaft passes through the magnet, the rotor, and the second case, and is rotatably disposed on the first case. A weight is exposed by the second case, and connected to the shaft passing through the second case. The weight rotates along with the shaft to generate vibration. The vibration of the weight is transmitted to the housing.
Further, as battery life in the mobile communication device diminishes between charges, the vibration can be adversely affected. In short, the vibration degrades as available power to the vibratory motor decreases, as is typical between charges of the battery. It would be advantageous and/or desirable to be able to provide a relatively constant and/or consistent vibration despite variations in battery voltage.
Accordingly, it can be seen that a need exists for a method and apparatus for controlling a vibration motor for a mobile communication device, so as to provide a substantially consistent vibration despite fluctuations in voltage of the battery. It is to the provision of such a method and apparatus that the present invention is primarily directed.